U.S. Pat. No. 3,203,188 discloses a method and apparatus for preparing a trench for a subsurface conduit line and for laying such a line. A conventional trench digging machine which includes a vertically adjustable frame supporting a power driven digging wheel with digging buckets mounted to the periphery of the wheel allows for digging trenches at different depths.
A chain and sprocket drive is utilized to drive the wheel. The earth is treated to separate the fine particles from the larger particles through the use of mesh. The screen or mesh is inclined so the rocks will gravitate to the shoot. After the particles are separated, the fine particles of the earth are deposited on the bottom of the trench to act as a cushion pad on which the conduit can be laid. A conveyor belt transfers the fine particles to the bottom of the trench and a leveling shoe adjusts the mound to give the pad a depth which may be on the order of six or more inches.
U.S. Pat. No. 3,332,249 discloses a trench digging and refilling apparatus. The digger has a vertically oriented trench digging unit which is attached to a tractor. The digging unit continuously elevates dirt onto a circular conveyor which conveys the dirt and discharges it rearwardly into the trench after a continuously fed cable is placed in the trench between the locations of digging and refilling.
U.S. Pat. No. 3,905,200 discloses a cable laying attachment for vehicles. The attachment has an elongated beam member to connect to the front end of the vehicle. A support arm is arranged as a tubular structure which can telescope. A plow blade carrier, a plow and a cable shoe are carried at the rear end of the beam member. During the course of plowing, the plow blade is positioned in a straight longitudinal position relative to the path of movement of the tractor. The cable is fed through the shoe as it is supplied from a drum. The cable is fed over the pulley and into a guide shoot in the shoe. The vertical positioning of the beam member is accomplished by the support arm through the medium of cylinder members. The depth of the plow is accomplished through suitable actuation of the cylinder. As the plow travels through the ground, the cable is laid immediately afterwards in its desired vertical position.
U.S. Pat. No. 5,174,685 discloses a flexible pipe laying and covering apparatus. This apparatus lays the flexible pipe in a trench embedding it within a bed of gravel in a single operation. A gravel hopper, a guide sleeve, and a skid or sled allows the apparatus to be dragged through the trench, lay the pipe, and fill around the pipe with gravel. The apparatus permits pipe to be laid without requiring personnel to be located within the trench thus avoiding the increased costs required by OSHA regulations for tapering the trench walls or bracing them to avoid cave-in.
U.S. Pat. No. 4,397,585 discloses an apparatus for inserting foldable conduit below ground. A plow forms a cavity in the ground for receiving conduit and the conduit is conveyed through a feeder from a conduit reel of some sort. As the conduit passes through the feeder the conduit is unfolded. Soil lifted by the plow falls around the unfolded conduit constraining it to its unfolded configuration.
U.S. Pat. No. 4,812,078 discloses a mechanized unit for digging a trench and laying elongated objects, the mechanized unit has a motorized vehicle, a digging wheel connected to the rear of the vehicle, a conduit device for holding the coiling conduit at the front of the vehicle, a guide device for laying the conduit in the trench, a soil shoot of some sort for laying the conduit in the bottom of the trench and covering the conduit with the soil.
U.S. Pat. No. 4,825,569 discloses a trench digging, cable laying and trench filling apparatus, the apparatus uses a safety shield to direct the previously excavated dirt back into the trench, the apparatus has a cable laying device which lays the cable in the trench before refilling the trench with dirt, a spool of cable supported on a rod and the cable is fed into the open trench ahead of the loose dirt which is then covered by the loose dirt.
U.S. Pat. No. 5,743,675 discloses an underground cable anode installment system. The system has a plow which creates a tunnel, conduit is delivered into the tunnel, a shoot feeds the conduit into the tunnel, also a coke breeze can be delivered to the tunnel by passing it over the nonmetallic inner surface of the shoot to provide for horizontal encasement of the anode cable.
U.S. Pat. No. 5,913,638 discloses a sand channel trenching and pipe laying apparatus. The apparatus is connected to a motor driven vehicle which has an elongated frame with a turf cutting assembly which includes a couple of vertical cutting blades for removing a strip of turf. A pipe dispenser for laying in position the pipe in the channel is secured to the sub frame mounted on the rearward portion of the frame. A sand funnel is linked to a sand hopper and mounted on the same sub frame as the pipe layer. Sand is forced through the shoot into the trench. The sand covers the pipe and fills the trench.
U.S. Pat. No. 6,478,508 discloses an apparatus for laying underground electric cables, where a vehicle is towed along a trench and carries a van and a depositing unit which forms the base layer of an inner material for heat dissipation at the bottom of the trench upon which high-voltage lines are carried. The second van carries a second depositing unit which forms the cover of the inert material above the cable and the first layer.
U.S. Pat. No. 6,622,403 discloses a backfill and grading apparatus. The apparatus deposits material within the trench. The apparatus has a hopper and an elongated shoot which extends down from the hopper into the trench. The apparatus has a gate between the hopper and the shoot for controlling material flow out of the hopper, through the shoot and into the trench. The apparatus is mounted on the back of a trailer with a variably positionable mount and includes a laser guided control system to maintain the deposit material at the predetermined grade.
Referring to Col. 3 around line 33, in an exemplary embodiment, the apparatus is coupled to a tractor by a hydraulic mount that variably positions the apparatus up and down along a substantially vertical axis with respect to the tractor. The hydraulic mount has a control element that controls the vertical position of the apparatus response to input signals from the operator. Thus the position of the apparatus can be made subject to automatic control of the operation of control element in connection with or as part of an automatic control system. Referring to Col. 4 at line 27, an operator digs a trench and bedding is installed in the trench. Pipe is then installed in the trench and placed on the bedding and then covered to the predetermined grade with the appropriate material.
U.S. Pat. No. 6,854,931 discloses an apparatus for establishing adjustable depth bed soil in trenches for utility lines and encasing the lines. The unit places a predetermined and adjustable depth of selected bedding material on the bottom of the trench in the ground, then places on the bed a continuous length of utility line having a predetermined spatial relationship with each other and then encases utilities with additional select material to a predetermined and adjustable depth in a continuous operation. A single hopper is used to form the bed for both utility lines. An adjustable height blade is provided which both sets the blade height and also smooths the bed surface for each utility line.
Trenchers
U.S. Pat. No. 6,708,430 discloses a trencher for digging trenches, referring to the summary of the invention section in column one around line 52, “one aspect of this invention relates to a trencher for digging trenches. The trencher comprises a trencher frame. A chain bar is secured at one end to the trencher frame to extend outwardly from the trencher frame in a cantilever manner. An endless chain having digging teeth is provided with the endless chain being carried on the chain bar. The chain bar comprises a base member secured to the trencher frame which base member carries a stub having a longitudinal axis, an elongated boom having a socket at one end which socket is slipped over the stub of the base member, a slot in the stub with the slot extending parallel to the longitudinal axis of the stub, and at least one bolt passing through the boom and the slot to secure the boom to the stub.”
U.S. Pat. No. 7,096,609 discloses a trencher unit, referring to the brief description of the invention in column one around line 43, “The trencher unit of the present invention is a unit that can be mounted to a standard attachment plate of a loader such as a typical skid steer loader. The trencher unit relies on the auxiliary hydraulic power of a loader and can be operated in an upright orientation to dig curved trench sections. The trencher unit includes a support frame having an attachment fitting at its proximate end for mounting to the attachment plate of a loader. A chain drive sprocket is rotatably mounted to the support frame near the proximate end of the support frame. An idler wheel is mounted to the support frame at the distal end of the support frame. The chain drive sprocket and the idler wheel carry an endless digging chain which presents a series of digging teeth. A hydraulic chain drive motor for driving the chain drive sprocket and the digging chain is mounted to the support frame. Auxiliary hydraulic lines which communicate with the loader hydraulic system supply the hydraulic chain drive motor with pressurized hydraulic fluid. An auger assembly situated on the support frame between the drive sprocket and the idler wheel includes augers for pushing dirt away from the digging chain.”
U.S. Pat. No. 6,249,983 discloses a trencher assembly utilizing a direct drive motor, referring to the disclosure of the invention section in column 2 around line 1, “In one aspect of the present invention, a trencher assembly comprises a frame. A boom arm is connected on the frame. A motor is connected on the frame and has a rotatable shaft. A sprocket is connected on the shaft of the motor. The sprocket is directly driven by the motor through the rotation of the shaft. A digging chain is connected between the boom arm and the sprocket and is driven by the rotation of the sprocket. An auger assembly is connected to the sprocket for rotation therewith in unison with the digging chain.”